In a power semiconductor module of which a semiconductor element is mounted on an insulating substrate, an electrode of the semiconductor element is connected electrically to a circuit plate of the insulating substrate with a bonding wire. Recently, a power semiconductor module employing a conductive post instead of the bonding wire is known as disclosed in Patent Literatures 1 and 2. In the power semiconductor module employing the conductive post, one end of the conductive post is connected to the electrode of the semiconductor element, and one end of another conductive post is also connected to the circuit plate of the insulating substrate. Further, the other ends of these conductive posts are connected to wiring film of a printed circuit board which is set so as to face the insulating substrate on which the semiconductor element is fixed. Then this results in an electrical connection between the semiconductor element and the circuit plate of the insulating substrate. The power semiconductor module having such a structure can be miniaturized in comparison with the power semiconductor module having the bonding wire, and have advantages of reducing the inductance of the wiring and accommodating high speed switching.
Moreover, for the power semiconductor module, a resin case in which the semiconductor element and the insulating substrate are accommodated has been filled and sealed with silicone gel. Furthermore, it is recently known that the semiconductor element and the insulating substrate are sealed with insulating thermosetting resin molded by transfer molding in the power semiconductor module. As described above, when sealed with the transfer molded resin, various members such as the semiconductor element and a printed circuit board located inside can be fixed with the resin. Then this leads the power semiconductor module to attain high reliability against power cycle when it is in use.